Cesar Cortinas was a Uruguayan composer whose work displays a mix of European Romantic traditions and Latin American lyricism. This Ballade is defined by its introspective, song-like structure.
Independence between the active left-hand accompaniment and the singing right-hand melody is the primary technical requirement.
Comparable difficulty and character — good candidates for what to learn next.
Balada Op 4 is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 7.
You should be comfortable at Henle level 5 — meaning you can already play level 4–5 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of Balada Op 4 lasts about 5 minutes.
Balada Op 4 is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include Berceuse by Georges Bizet, Berceuse sur le nom de Gabriel Fauré by Maurice Ravel, Berceuse sur le nom de Gabriel Fauré, M.74 by Maurice Ravel — see the full similar-pieces list on this page.